The present invention relates to an aerobic reduction reactor and more particularly to an improved biological reactor which is particularly adapted for rapid oxidation reduction of solid organic wastes on a continuous flow basis.
In carrying out the variety of oxidation processes which have been proposed in the waste management field, it has been common to utilize an elongated, cylindrical vessel to enclose and enhance the decomposition of organic wastes. As shown in U.S. Pat. No. 2,241,734-Peterson and U.S. Pat. No. 2,954,285-Carlsson et al, a cylindrical container or vessel is typically mounted on rollers for rotation about its longitudinal axis. A discharge opening is provided in one end of the vessel and a loading or feed opening is provided in the opposite end. A hopper and associated feed mechanism are positioned adjacent the feed opening to supply waste material to be processed within the vessel. A fan or blower is frequently employed to draw or force air through either opening and into contact with the waste material in the vessel to provide the oxygen necessary for the aerobic reduction process.
Aerobic biological conversion vessels, such as described in the Peterson patent and as suggested by the patentee, may be combined with sorting devices, grinding mills, conveyors, drying apparatus, etc. to form an industrial plant, but are not readily adaptable to on-site, stand alone waste reduction applications because of the problems encountered in handling of the waste materials. For the best efficiency of such biological conversion vessels, the waste material should be dropped into the hopper in a continuous stream so it can be fed into the vessel to maintain the oxidation process at a constant level. However, the typical dairy barns, feedlots and poultry houses are not cleaned continuously, but rather, only at certain intervals. Therefore, provision must be made to accumulate the waste material and then dispense it to the vessel in a constant stream . This usually takes the form of a relatively large storage bin of an inverted cone or inverted pyramid configuration in association with a conveyor system to move the material from the bin to the hopper. The convergent walls of the storage bin define a relatively narrow opening at the bottom of the bin through which a continuous stream of material is directed by gravity onto the conveyor for transport to the biological conversion vessel. Such apparatus works well with dry, granular or similar discrete-particle materials which tend to pour easily. However, moist or wet solid waste materials, particularly when combined with sawdust, straw or other bedding materials, are not of uniform consistency and tend to clump together and to bridge between the convergent walls of the storage bin, thus disrupting the flow of material onto the conveyor. To overcome this problem, as well as the tendency of the moist waste material to clog the conveyors, and to thereby maintain a constant stream of material to the biological conversion vessel has required pre-conditioning the material with specialized equipment which is expensive to install and to maintain.
To facilitate close control of the environment within the rotating vessel it has been proposed to provide temperature and/or humidity monitoring devices and air supply and evacuation tubes inside the vessel, such as shown by U.S. Pat. No. 5,591,635-Young et al and U.S. Pat. No. 4,028,189-Fagerhaug et al. Since such control devices require at least occasional maintenance or replacement, some means, such as access ports, must be provided for entry into the interior of the vessel. Such access ports typically take the form of removable covers or hatches which are aligned with openings provided in the cylindrical surface of the vessel. The initial construction of such access ports is both time consuming and expensive and the use of them to gain access to the equipment mounted within the vessel requires the biological conversion process to be shut down and the vessel to be at least partially emptied. The control permitted with such equipment is thus obtained only at the price of substantial increase in costs of both the initial construction and subsequent operation of the resultant conversion vessels.
The present invention avoids the shortcomings of the prior known waste material biological conversion equipment by provision of an aerobic reduction reactor in which material handling requirements are minimized, maintenance procedures are simplified and operational shut down of the biological conversion process for equipment maintenance or repair is virtually eliminated.
The above objects are realized in the present invention by the provision of a dual chamber aerobic reactor which includes a generally rectangular blending chamber in which the biological process is initiated in a biomass while it is being blended, and an elongated cylindrical vessel operatively connected to the blending chamber in which the oxidation reduction of the biomass is completed. The blending chamber is stationary and has a smaller capacity than the cylindrical vessel which is mounted on rollers for rotation about its longitudinal axis. The blended biomass is continually moved from the chamber into the vessel by a combination of gravity and rotation of the vessel. A blower is provided to draw air into the reactor to feed the aerobic reduction process and to evacuate gases produced by the process, and means is provided for monitoring the environment within the reactor from the exterior of the vessel and chamber.